Electron-discharge devices



p 9, 1969 c. A. LOWERY, JR., ET AL 3,465,401

ELECTRON-DISCHARGE DEVICES Original Filed June 22, 1964 INVENTORS Charles A. Lowerym Mark J Videka y Attorney k K 8 rm 2 om g NGHWN- United States Patent US. Cl. 2925.16 2 Claims ABSTRACT OF THE DISCLOSURE A method for establishing a series electrical circuit between the three heaters of a tri-gun cathode-ray tube. A metallic strip is formed into a closed loop, and pairs of heater terminals are struck from the strip at spaced intervals corresponding to the relative locations of the threeguns of the tube. Support tabs are struck from the portion of the strip intervening between the relative locations of the three guns, and these are fixed to insulating support elements within the tube to hold the loop assembly in position. After connecting the heaters across respective ones of the heater terminal pairs, the metallic strip is severed between the terminals to establish a mechanically rugged series electrical connection between the three heaters. The method involves only the use of simple and economical punching and forming techniques and is readily adapted to application with automatic equipment.

This application is a division of copending US. application Ser. No. 376,828, filed June 22, 1964, by the present applicants.

This invention relates to electron-discharge devices and more particularly to plural-beam cathode-ray tubes of the type having a plurality of electron guns assembled in a predetermined array by means including a plurality of insulating support elements. More specifically, the invention is directed to a method of manufacturing such heater assemblies.

In a conventional tri-color television picture tube, three separate electron beams are simultaneously projected through an aperture mask onto a mosaic type of phosphor screen. To this end, three separate electron guns, one for each of the primary colors, are provided in the neck, each of the guns being equally spaced from the geometrical axis of the tube in what maybe considered a triangular or delta array. Each electron gun is provided with a thermionic cathode having an associated resistance heater element, and means must be provided to pass electric current through the heater elements in order to achieve the required thermionic emission.

In accordance with conventional practice, the three electron guns and all of their electrode elements are preassembled in a unitary gun mount by means including a plurality of support elements, usually in the form of three longitudinally extending glass or ceramic support pillars. The gun-mount must be preassembled with a high degree of precision, and should be as compact as possible to permit the use of a relatively small neck diameter to avoid unnecessary complication in the associated deflection and conversion yoke assemblies, which, in use in a color television receiver, are mounted externally on the neck.

It is an object of the present invention to provide a new and improved method of forming a heater assembly for a plural-beam cathode-ray tube such as a color television picture tube.

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In accordance with the invention, a new and improved method of manufacturing a heater assembly for a pluralbeam cathode-ray tube having a trio of electron guns assembled in a predetermined array by means including a plurality of insulating support elements, comprises forming a strip of conductive material in a substantially closed loop adapted to be encompassed by the array of insulating support elements, striking at spaced portions of the strip corresponding to the relative spaced locations of the three guns of the cathode-ray tube a plurality of pairs of heater terminals, one pair for each of the guns, striking from each of the portions of the strip intervening between the relative spaced locations of the electron guns at least one tab for connection to an assigned one of the support elements, fixing the tabs to the support elements, connecting across each pair of heater terminals a heater for one of the guns, and severing the strip between each pair of heater terminals to connect the heaters in series-circuit relationship.

The features of the present invention which are believed to be novel are set forth with particularity in the appended claims. The invention, together with further objects and advantages thereof, may best be understood by reference to the following description taken in connection with the accompanying drawing, in the several figures of which like reference numerals identify like elements, and in which:

FIGURE 1 is a perspective view of an electron gunmount assembly for a color television picture tube, embodying the present invention;

FIGURE 2 is a perspective view of a heater assembly employed in the gun-mount assembly of FIGURE 1 and embodying the invention;

FIGURE 3 is a cross-sectional view taken along the line 33 of FIGURE 1; and

FIGURE 4 is a fragmentary cross-sectional view, taken along the line 4-4 of FIGURE 3.

The gun-mount assembly of FIGURE 1, for use in a tri-color television picture tube, comprises three electron guns assembled in a triangular or delta array, only one of the guns being visible in the view of FIGURE 1, by means including three longitudinally extending insulating support members for pillars 10, of which only two are visible in the view of FIGURE 1. Each of the electron guns includes a thermionic cathode assembly 11, a first control grid (G 12, a screen grid or first'auode (G 13, and a pair of focusing electrodes 14 and 15. A common convergence subassembly 16, common to all three electron guns, is also provided at the output end of the gun-mount assembly and is provided with spring contacts for connection to the final anode (not shown). The preassembled triple gun-mount is supported on a glass press 18 which is provided with a plurality of lead-in conductors 19 and an exhaust tubulation 20 in conventional manner. The individual gun electrodes, the support arangement, and the press may all be of conventional construction, although certain features of the illustrated cathode assembly 11 and of the convergence electrode 16 and its assembly to the remaining elements of the gun-mount are described and claimed in the two copending applications of Joseph P. Flore, filed concurrently herewith, entitled Electron-Discharge Devices and Cathode-Ray Tubes, respectively, and both assigned to the same assignee as the present application.

As best shown in FIGURE 4, the cathode assembly 11 for each of the electron guns includes a tubular cathode sleeve 21 on the end of which is provided a thermionic emissive coating 22. Cathode assembly 11 further comprises a shield member 23 and a support flange 24 fixed to insulating support elements 10, as more particularly described and claimed in the above-mentioned Fiore application. Within each of the cathode sleeves 21, there is provided a conventional resistance heater element having a pair of heater leads 26 and 27. In the ensuing description, corresponding single-primed and doubleprimed reference indicia will be employed to designate the corresponding elements of the other two electron guns not shown in FIGURE 1.

The heater assembly comprises a plurality of longitudinally aligned thin, fiat metallic strips in an array corresponding to the electron gun array and generally defining a substantially closed loop, as best shown in FIGURE 2. The array of strips comprises a pair of intermediate sections 30 and 31 respectively extending between and int-erconnecting a lead of the heater element associated with one of the cathodes to a lead of the heater element associated with the next adjacent cathode. Specifically, intermediate section 30 extends between and interconnects heater lead 27" and heater lead 26', while intermediate section 31 extends between and interconnects heater leads 27' and 26. The loop array of FIGURE 2 further comprises a pair of terminal half-sections 32 and 33 respectively connected to the remaining leads 27 and 26" of an adjacent pair of heater elements.

Intermediate section 30 is provided with a pair of upstanding integral tabs 34 and 35 to which is afiixed an outwardly projecting rigid extension member 36 adapted to be fixed to one of the insulating support elements 1t). Similarly, intermediate section 31 is provided with a pair of upstanding integral tabs 37 and 38 to which is affixed an outwardly projecting rigid extension member 39 adapted to be fixed to another of the insulating supporting elements 10. Extension members 36 and 39 each include inwardly projecting abutments 36a and 39a which abut against intermediate sections 30 and 31 respectively to index the heater connection loop longitudinally during assembly. Terminal half-sections 32 and 33 are provided with integral upstanding end tabs 40 and 41 respectively, to which are afiixed adjacent closely spaced outwardly projecting rigid extension members 42 and 43 respectively, and members 42 and 43 are fixed to the third insulating support element 10 (FIGURES 3 and 4).

To facilitate the connection of heater leads 26, 27, 26 27, 26" and 27" to connection strips 30-33 inclusive, the strips are provided with a pair of integral marginal longitudinally spaced outwardly projecting heater connectlon tabs or terminals 44 and 45, at opposite edges of the strlp and each of a width less than half that of the str1p, at each of three substantially equally spaced locations corresponding to those of heater elements 25 in the electron gun array. Heater leads 26 and 27 are spot welded to heater terminals 44 and 45, a similar construct on being employed for the correspondingly numbered primed and double-primed elements associated with the other two electron guns. Similarly, extension members 36, 39, 42 and 43 are spot welded to support tabs 34, 35, 37, 38, 40 and 41.

In accordance with the present invention, the heater connection assembly of FIGURE 2 is preferably formed initially of a single resilient thin flat metall c strip of substantially uniform width which is formed wlth its ends in adjacent closely spaced relation into a substantlally closed loop. Support tabs 34, 35, 37, 38, 40 and 41, as well as heater connection tabs or terminals 44, 45, 44, 45, 44" and 45", are struck from the connection loop itself and bent outwardly, by conventional punching and forming techniques. Extension members 36, 39, 42 and 43 are fused into insulating support pillars 10, following which the heater connection loop is slipped into position against abutments 36a and 39a in the manner illustrated in FIGURE 2 and extension members 36, 39, 42 and 43 are welded to their respective support tabs. Heater leads 26 and 27 (and the correspondingly numbered primed and double-primed heater leads of the other electron guns) are connected to the heater connection tabs or terminals 44 and 45 (and correspondingly numbered primed and double-primed tabs), after which the remaining narrow bridge sections 46 are severed, and an intermediate portion of bridge sections 46 preferably removed, to place the heater elements 25 in a single series circuit. A pair of lead-in conductors 47 and 48 extending through glass press 18 are respectively connected to extension members 42 and 43, as by the use of the intermediate spot Welded connection tabs 49 and 50 (FIGURE 4), to provide means for supplying electric current to heater elements 25 in series.

The fabrication of the heater connection assembly has been described in a preferred sequence of manufacturing steps, but other sequences may be employed without departing from the invention. For example, bridge sections 46 may be severed before connecting the heater leads to terminals 26 and 27.

Thus the present invention provides a novel heater connection assembly for use in a plural-beam cathode-ray tube such as a tri-color television picture tube. The construction is inexpensive and simple to employ, and is readily adaptable to commercial production on a large scale. The method of assembling the heater connection assembly of the present invention is particularly attractive because it involves only the use of simple and economical punching and forming techniques and is readily adapted to application with automated equipment. The resulting construction is rugged and durable, both from the point of view of physical stability and continuity of the heater current circuit.

While a particular embodiment of the invention has been shown and described, it will be obvious to those skilled in the art that changes and modifications may be made without departing from the invention in its broader aspects, and, therefore, the aim in the appended claims is to cover all such changes and modifications as fall within the true spirit and scope of the invention.

We claim:

1. The method of manufacturing a heater assembly for a plural-beam cathode-ray tube having a trio of electron guns assembled in a predetermined array by means including a plurality of insulating support elements, which method comprises:

forming a strip of conductive material in a substantially closed loop adapted to be encompassed by said array of insulating support elements;

striking at spaced portions of said strip corresponding to the relative space locations of the three guns of said cathode-ray tube a plurality of pairs of heater terminals, one pair for each of said guns;

striking from each of the portions of said strip intervening between the relative space locations of said electron guns at least one tab for connection to an assigned one of said support elements;

fixing said tabs to said support elements;

connecting across each pair of heater terminals a heater for one of said guns;

and severing said strip between each pair of said heater terminals to cause said heaters to be interconnected in electrical series-circuit relationship by segments of said conductive supporting loop. 2. The method of manufacturing a heater assembly for a plural-beam cathode-ray tube having a trio of electron guns assembled by support elements arranged in a triangular array which comprises;

forming a thin flat strip of conductive material into a loop adapted to be accommodated within said array;

striking from the marginal edges of equi-spaced portions of said loop corresponding to the relative space locations of said electron guns a plurality of pairs of longitudinally spaced heater terminals, one pair for each of said guns and each terminal being of a width less than half that of said strip and each such pair of terminals being laterally separated by a bridge section of reduced width;

striking from each of the portions of said 100p intervening between the relative spaced locations of said electron guns and corresponding to the location of said support elements in said array a plurality of tabs for connection to an assigned one of said support elements;

fixing said tabs to said support elements;

connecting across each pair of heater terminals a heater for one of said guns;

and severing said bridge sections between each of said pair of heater terminals to cause said heaters to be in electrical series-circuit relationship by segments of said conductive supporting loop.

References Cited UNITED STATES PATENTS 2,486,065 10/1949 Saucet 29-25.11 X 2,508,979 5/1950 Van Gessel 2925.13 2,638,660 5/1953 Van Gessel 2925.15 3,134,923 5/1964 Brown 313--27l JOHN F. CAMPBELL, Primary Examiner 10 R. B. LAZARUS, Assistant Examiner US. Cl. X.R. 

